Low-density RRIM using mineral fiber filler

ABSTRACT

The invention pertains to a low weight, low density rigid polyurethane-polyurea reinforced reaction injection molded (RRIM) part having wollastonite reinforcing fibers dispersed throughout a matrix made by reacting polyisocyanates with a resin containing hydroxy group tertiary amine polyether polyols, a water as a blowing agent, and optionally surfactants, chain extenders, and urethane promoting catalysts. The low density RRIM part using wollastonite and the tertiary amine polyether polyols is a low cost alternative to glass fiber reinforced low density parts, and the part exhibits good mechanical properties and quick demold times.

This is a division of application Ser. No. 07/914,080 filed Jul. 16,1992, U.S. Pat. No. 5,208,269.

FIELD OF THE INVENTION

The subject invention relates to the field of fiber-reinforced reactioninjection moldings. More particularly, the subject invention pertains toreactive systems containing hydroxyl functional tertiary amine polyols,preferably without the presence of chain extenders, as the matrix forwollastonite fiber-reinforced water-blown moldings useful as interiordoor panels, overhead and center consoles, package trays, and instrumentpanel substrates.

DESCRIPTION OF THE RELATED ART

Reaction-injection-molding (RIM) systems by now are well known to thoseskilled in the art. Commercial systems produce elastomeric productscontaining polyurethanepolyurea linkages which have many uses, forexample, as automobile facias. However, such systems have relatively lowheat distortion temperatures and lack the flexural modulus and tensilestrength necessary for many applications. The chemistry of thesereactive systems involves the use of a polyisocyanate "A side" (Acomponent) and a "B side" employing a mixture of compounds containingisocyanate-reactive hydrogens. These "B side" components generallyinclude one or more hydroxyl-functional polyether or polyester polyolsand one or more sterically hindered diamines. The polyol componentsreact with the isocyanate to form urethane linkages while the aminecomponents react to form urea linkages. Such systems are disclosed, forexample, in Weber U.S. Pat. No. 4,218,543.

To improve the flex modulus and tensile strength of RIM parts, woven ornon-woven fiber reinforcement glass mats have been used. Such mats arecut into the shape of the molding and laid up on a mold surface. Thephysical handling of the mats is often irritating to the skin, difficultto handle, and requires time to cut and lay into the mold.

Other methods of improving the flexural modulus and tensile strength ofRIM parts is to mix short, chopped fibers into the resin B sidecomponent and inject the fiber-containing resin with isocyanate into themold (RRIM). This process is also well known and has been proposed as ameans for the manufacture of high density parts requiring strength inapplications such as exterior automotive body parts. Various types offillers, such as mica, glass, and wollastonite have been proposed asreinforcing agents in high density RRIM. For example, U.S. Pat. Nos.5,036,118, 4,943,603, and 4,871,789 describe the use of mica orwollastonite as reinforcement predominately in high density (>1.0specific gravity) RRIM systems, suitable for use in exterior bodypanels.

More recently, the use of RRIM for interior automotive parts has beeninvestigated. In the wake of ever increasing standards for increasingfuel efficiency, the industry is continuously seeking means to reducethe weight of automotive parts while maintaining its necessaryfunctional strength. Accordingly, for interior body parts where flexuralmodulus, tensile strength, and impact resistance requirements are not asstringent as in exterior body panels, low density RRIM parts have beeninvestigated as alternatives to heavier weight metal, wood fiber, ABSand PP interior parts. Glass reinforcement in low density RRIM has beenproposed. However, such reinforcement is relatively expensive.

As part of the subject invention, the inventor has discovered that whencombined with a particular matrix resin, wollastonite is an excellentalternative for glass fiber reinforcement in low density RRIM, atapproximately one-third to one-half the cost of glass. It has also beenfound that using hydroxyl functional tertiary amine polyether polyols,one can produce a RRIM part having good flexural modulus, tensilestrength, and impact resistance. Such a polyol also reduces the demoldtime and, in one embodiment, reduces the viscosity of the resin forgreater ease in processing, does not require the use of chainextenders/crosslinkers, and requires reduced amounts of urethane formingcatalysts.

SUMMARY OF THE INVENTION

The subject invention relates to low weight, low density rigidpolyurethane-polyurea RRIM parts employing wollastonite reinforcingfibers dispersed through a matrix comprising the reaction product of anisocyanate component and a resin component containing hydroxyl grouptertiary amine polyether polyols, blowing agent, preferably consistingof water, and optionally a urethane-promoting catalyst, chain extender,and a surfactant.

DETAILED DESCRIPTION OF THE INVENTION

The reinforcing filler of the subject invention is an acicularwollastonite preferably having an aspect ratio of greater than 2, morepreferably 10 or greater, to improve the flexural modulus and tensilestrength. The wollastonite preferably has an average particle lengthranging from 0.005 inch to 1 inch, more preferably from 0.03 to 0.25inch, with one-sixteenth inch milled or chopped fibers being the mostpreferred.

The wollastonite particles are preferably surface treated to improveadhesion between the particle and the polymer matrix. The surfacetreatment employed may be a coating treatment applied to the surface ofthe particle as a chemical modification to the filler. Surface treatingagents and methods are well known to those of skill in the art andinclude aminoalkyl, chloro, epoxy, vinyl, and/or isocyanate silanecoupling agents as disclosed in U.S. Pat. Nos. 5,096,644, 4,582,887,4,374,210, 4,444,910, 4,218,510, 4,296,945, 4,689,356, and 4,585,803,all hereby incorporated by reference; latex compositions as disclosed inU.S. Pat. No. 4,800,103 to Jiffs, hereby incorporated by reference; andtitanate coupling agents as disclosed in Adhesion and Bonding inComposites, Ryutoko Yosomiya et al., Marchel Dekker, Inc., New York1990, pp. 110-154, hereby incorporated by reference. Preferred are theepoxy, chloro, isocyanate, and amino silane coupling agents.

Suitable amounts of wollastonite dispersed throughout the part rangefrom 10 weight percent to 20 weight percent based on the weight of thetotal composition, preferably from 13 weight percent to 17 weightpercent; or from about 20 weight percent to about 30 weight percentbased on the weight of the B side resin component, with from about 25weight percent to 30 weight percent being preferred. One may add lessthan the stated amounts of reinforcement; however, much of the desiredstrength is lost as the composite approaches the properties of anunreinforced part. The stated upper limits may also be exceeded;however, while the flexural modulus will increase, the elongation andimpact resistance decreases producing a brittle part. Thus, adding thestated range of reinforcement produces a part with optimal overallmechanical properties.

The wollastonite reinforcement may optionally be admixed with otherchopped fibers or fillers in the polyol side or added to the isocyanateside in amounts such that the total fiber and filler reinforcement inthe composite does not appreciably degrade the physical properties of acomparable composite containing solely wollastonite in amounts of 30weight percent or less. It is desirable to add about 50 weight percentor less /f the other fibers or fillers such that the physical propertiesand expense of the part are predominately determined by wollastonitereinforcement.

Suitable additional fibers include man-made glass fibers, carbon fiber,silicon carbide fiber, metal fibers, ceramics and the like, and naturalreinforcement such as flaked mica, jute, and cellulose fibers. Fillersinclude flaked or milled glass, carbon black, talc, mica, calciumcarbonate, bauxite, and the like.

The composite of the subject invention is a low density part possessinghigh flexural modulus while maintaining its impact strength. The densityof the composites have a specific gravity of 1.0 or less, preferablyfrom 0.4 to 0.65. The flexural modulus of the composite is greater thanabout 50,000 psi at 72° F., preferably greater than 100,000 psi, morepreferably greater than 125,000 psi at 72° F. The impact strength of thecomposite has a Gardner impact strength of at least 0.4 ft./lb. at 72°F., preferably 0.5 ft./lb. or more, more preferably 0.8 ft./lb. or more.The heat distortion temperature of the composite is greater than 120°F., preferably 130° F. or greater at 264 psi.

The reactive components of the subject invention RRIM systems compriseone or more polyisocyanates and an isocyanate-reactive resin componentcomprising a hydroxyl-functional tertiary amine polyether polyol. In thelow density (cellular) RRIM systems of the invention, theisocyanate-reactive component may further contain up to about 50 weightpercent based on the B side resin component of a conventional or graftpolyol and/or low molecular weight chain extender. Traditionalpolyurethane-polyisocyanurate system components such as flameretardants, catalysts, UV stabilizers, surfactants, dyes, and pigmentsmay also be added when necessary or desirable.

Organic polyisocyanates which may be employed include aromatic,aliphatic, and cycloaliphatic polyisocyanates and combinations thereof.Representative of these types are the diisocyanates such as m-phenylenediisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate,mixtures of 2,4- and 2,6-toluene diisocyanate, hexamethylenediisocyanate, tetramethylene diisocyanate, cyclohexane-1,4-diisocyanate,hexahydrotoluene diisocyanate (and isomers),naphthalene-1,5-diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, 2,2'-,2,4'-, and 4,4'-diphenylmethane diisocyanate, 4,4'-biphenylenediisocyanate, 3,3'-dimethoxy-4,4'-biphenyl diisocyanate,3,3'-dimethyl-4,4'-biphenyl diisocyanate, and3,3'-dimethyldiphenylmethane-4,4'-diisocyanate; the triisocyanates suchas 4,4',4"-triphenylmethane triisocyanate, and toluene2,4,6-triisocyanate; and the tetraisocyanates such as4,4'-dimethyldiphenylmethane-2,2'-5,5'-tetraisocyanate; andpolymericpolyisocyanates such as polymethylene polyphenylenepolyisocyanate. Especially useful due to their availability andproperties are 4,4'-diphenylmethane diisocyanate and polymethylenepolyphenylene polyisocyanate.

Crude polyisocyanates may also be used in the compositions of thepresent invention, such as crude diphenylmethane isocyanate obtained bythe phosgenation of crude diphenylmethane diamine. The preferred orcrude isocyanates are disclosed in U.S. Pat. No. 3,215,652.

Also useful are the modified polyisocyanates, examples of which includeuretoniminecarbodiimide group containing polyisocyanates (German patentNo. 10 92 007), allophanate group containing polyisocyanates (BritishPatent No. 994,890; Belgium Patent No. 761,626), isocyanurate groupcontaining polyisocyanates (German Patent Nos. 10 22 789, 12 22 067, 1027 394, German Published Application Nos. 19 29 034 and 20 04 048),urethane group containing polyisocyanates (Belgium Patent No. 752,261,U.S. Pat. No. 3,394,164), biuret group containing polyisocyanates(German Patent No. 11 01 394, British Patent No. 889,050) and estergroup containing polyisocyanates (British Patent No.s 965,474,1,072,956, U.S. Pat. No. 3,567,763, German Patent No. 12 31 688), all ofwhich are hereby incorporated by reference.

Preferably used are the easily accessible, optionallyuretonimine-carbodiimide and urethane group-containing, aromatic di- andpolyisocyanates such as 2,2'-, 2,4'-, 4,4'-diphenylmethane diisocyanate(MDI), as well as any desired mixtures of these isomers, and mixtures of2,2'-, 2,4'-, 4,4'-diphenylmethane diisocyanate and polyphenylpolymethylene polyisocyanates (crude MDI). Preferably used is auretonimine-carbodiimide-modified 4,4'-MDI composition containing from10 weight percent to 40 weight percent modified MDI and 60 weightpercent to 90 weight percent 4,4'-MDI, optionally containing less than10 weight percent 2,2'- and 2,4'-MDI, the weight percentages based onthe weight of the uretonimine-carbodiimide-modified 4,4'-MDIcomposition. The weight ratio of uretonimine to carbodiimide ranges from20:1 to 1:1.

Quasi-prepolymers are also preferred, such as urethane-modified MDIobtained by reacting a low molecular weight (<400) polyhydric compoundwith 4,4'-MDI, the final product containing, for example, from 40 weightpercent to 60 weight percent urethane prepolymer and 40 weight percentto 60 weight percent 4,4'-MDI.

Other such modifications include forming a quasi-prepolymer by reactinga uretonimine-carbodiimide-modified, allophanate-modified, orbiuret-modified MDI with a low or high molecular weight polyhydriccompound.

The above-mentioned isocyanates may be used singly or as blends withother isocyanates to obtain the desired physical properties, viscosity,and freezing point. For example, crude MDI may be admixed with 4,4'-MDIand 2,4'-MDI; or one may blend the uretonimine-carbodiimide-modified MDIwith a urethane-modified MDI and /ptionally crude MDI. Such blends maythen, if desired, be reacted with a polyhydric compound to obtain aquasi-prepolymer.

The B side resin component contains a hydroxyl functional tertiary aminepolyether polyol prepared by oxyalkylating an aliphatic or aromaticamine with ethylene oxide, propylene oxide, or mixtures thereof.

Examples of suitable aromatic amines which are useful as initiatorsinclude the various phenylenediamines, toluenediamines, anddiphenylmethanediamines. Examples of suitable aliphatic amines includeethylenediamine, propylenediamine, 1,4-butanediamine, 1,6-hexanediamine,diethylenetriamine, triethylenetetraamine, and the like.Hydroxylalkylamines may also be useful, for example, 2-hydroxyethylamineand 2- and 3-hydroxypropylamine, bis(2-hydroxyethyl)ethylamine,tris(2-hydroxyethyl)amine and the like. The preferred initiators aremonoethanolamine, ethylenediamine, 2-hydroxylpropylamine, andbis(2-hydroxyethyl)-2-hydroxypropylamine.

The amine or hydroxyalkylamine initiators are oxyalkylated withsufficient alkylene oxide to convert at least one and preferably allamino groups to tertiary amino groups. Alkylene oxides may be mentionedsuch as ethylene oxide and propylene oxide. Mixtures of these alkyleneoxides may be used; or they or their mixtures may be used sequentiallyto form homopolymeric, block, heteric, or block-heteric polyetherpolyols. The process of preparation of such polyether polyols isconventional and is well known to those skilled in the art.

Preferred hydroxyl functional tertiary amine polyether polyols arepolyoxypropylated-polyoxyethylated monoethanolamines containing aprimary hydroxyl group cap, such as polyoxyethylene, from 5 weightpercent to 35 weight percent, preferably from 20 weight percent to 30weight percent. Additional preferred hydroxyl functional tertiary aminepolyether polyols are polyoxypropylated-polyoxyethylatedethylenediamines capped with polyoxyethylene groups in an amount from 5weight percent to 35 weight percent, preferably 10 weight percent to 20weight percent. Mixtures of these two polyols are also suitable,preferably in weight ratios of the monoethanolamine initiated polyetherpolyol to the ethylenediamine initiated polyether polyol from 9:1 to 2:1where no other polyol is admixed.

The B side resin component preferably contains from about 10 weightpercent, more preferably 20 weight percent to 100 weight percent ofhydroxyl group tertiary amine polyether polyol based on the weight ofall polyether polyols in the resin. Suitable amounts of the tertiaryamine polyether polyol contained in the resin component range from 10weight percent to 99 weight percent, preferably 20 to 99 weight percent,more preferably 50 to 99 weight percent, based on the weight of allreactive compounds in the B side resin component. Reactive compoundsinclude all ingredients except wollastonite fibers and other optionalroom temperature insoluble fillers and fibers. In a more preferableembodiment of the invention, all (100 weight percent) polyether polyolsin the resin consist of tertiary amine polyether polyols terminated withprimary hydroxyl groups; and the resin is devoid of any chain extendersor crosslinkers.

The average functionality of the hydroxyl functional tertiary aminepolyether polyols is from about 2.5 to 6, preferably about 2.8 to about4.0, with average equivalent weights being from about 50 to about 3,000.Polyols with lower functionalities and higher molecular weights tend tomake the low density foam more flexible and increases its impactstrength at the expense of flexural modulus. A lower molecular weight,high functionality polyol will increase the crosslinking density and theflexural modulus of the foam. It has been found that one mayadvantageously achieve a high flexural modulus by using highfunctionality polyols and maintain the impact strength of the foam byblending a low molecular weight polyol with a high molecular weightpolyol. Thus, in one preferred embodiment, a low molecular weighttri-functional polyol is blended with a high molecular weight tertiaryfunctional polyol to obtain a foam possessing good flexural moduluswhile maintaining a satisfactory impact strength.

One may blend in major or minor quantities polymer modified polyetherpolyols with the hydroxyl functional tertiary amine polyether polyols.One of such polymer modified polyether polyols is known as graftpolyols. Graft polyols are well known to the art and are prepared by thein situ polymerization of one or more vinyl monomers, preferablyacrylonitrile and styrene, in the presence of a polyol ether orpolyester polyol, particularly polyols containing a minor amount ofnatural or induced unsaturation. Methods of preparing such graft polyolsmay be found in columns 1-5 and in the Examples of U.S. Pat. No.3,652,639; in columns 1-6 and the Examples of U.S. Pat. No. 3,823,201;particularly in columns 2-8 and the Examples of U.S. Pat. No. 4,690,956;and in U.S. Pat. No. 4,524,147; all of which patents are hereinincorporated by reference. The use of graft polyols may increase theflexural modulus and tensile strength of the foam.

Non-graft polymer modified polyols are also suitable, for example, thoseprepared by the reaction of a polyisocyanate with an alkanolamine in thepresence of a polyol as taught by U.S. Pat. Nos. 4,293,470; 4,296,213;and 4,374,209; dispersion of polyisocyanurates containing pendant ureagroups as taught by U.S. Pat. No. 4,386,167; and polyisocyanuratedispersions also containing biuret linkages as taught by U.S. Pat. No.4,359,541. Other polymer modified polyols may be prepared by the in situsize reduction of polymers until the particle size is less than 20 μm,preferably less than 10 μm.

Also useful in minor amounts are amine initiated polyether polyols whichhave free amino hydrogens and hydroxyl-functional polyoxyalkylenemoieties, blended with the tertiary amine polyol. Such polyols areprepared as taught by U.S. Pat. No. 4,517,383, by oxyalkylating analiphatic or aromatic amine with a stoichiometric excess of alkyleneoxide, but utilizing an extraordinarily high amount of basicoxyalkylation catalyst which must be present at the onset ofoxyalkylation. Such dual-functionality asymmetric polyols create bothurethane and urea linkages in the finished product, and further have theadvantage of lower viscosities than their fully oxylated, symmetricalanalogues.

To promote fast demold times, it is preferable that at least one of thepolyether polyols, more preferably all of the polyether polyols, beterminated with primary hydroxyl groups rather than secondary hydroxylgroups.

Hydroxyl-functional and amine-functional chain extenders are optionaland include hydroxyl-functional chain extenders such as ethylene glycol,glycerine, trimethylolpropane, 1,4-butanediol, propylene glycol,dipropylene glycol, 1,6-hexanediol, and the like; and amine-functionalchain extenders such as the sterically hinder diethyltoluene diamine andthe other hindered amines disclosed in Weber U.S. Pat. No. 4,218,543:phenylene diamine, 1,4-cyclohexane-bis-(methylamine), ethylenediamine,diethylenetriamine, N-(2-hydroxypropyl)-ethylenediamine,N,N'-di(2-hydroxypropyl)ethylenediamine, piperazine, and2-methylpiperazine. In low density RRIM systems, the amount of chainextender is generally less than 30 weight percent based on the totalweight of the resin component, preferably less than 25 weight percent,more preferably no chain extender being present. In resin componentsexclusively containing hydroxyl functional tertiary amine polyols, chainextenders are not necessary.

Plasticizers may also optionally be used in the subject invention lowdensity RRIM systems. In low density RRIM, the amount of plasticizer isgenerally less than 25 weight percent of the total resin (B-side)component.

Mold releases, both external and internal, may be utilized. Internalmold releases are generally mixtures of long chain carboxylate salts,particularly ammonium and substituted ammonium stearates, and calciumand zinc stearates. External mold releases are well-known commercialproducts and include waxes and silicones.

In the low density RRIM systems of the invention, a blowing agent isnecessary. Water is the preferred blowing agent and may be used inamounts of up to about 4 weight percent, preferably less than 1.0 weightpercent, more preferably less than 0.5 weight percent, of the resin(B-side) component. The density of the foam decreases with increasingwater content. When water is used as the blowing agent, thepolyisocyanate component is increased proportionately. Calculating theamount of water required and isocyanate required are routinely performedby those skilled in the arts of polyurethane and polyisocyanurate foams.

Chlorofluorocarbons (CFCs) and other volatile organic compounds may alsobe used as blowing agents, either alone, or in conjunction with water.When used alone, CFC blowing agents and other halogenated organics suchas methylene chloride are generally used in amounts up to about 30weight percent of the polyol component, preferably from 15 to about 25weight percent. Other volatile organic compounds such as pentane,isopentane, acetone, and the like, are used in correspondingly lesseramounts due to their lower molecular weights. When co-blown, theCFC-type blowing agents are utilized in lesser amounts, for example, upto about 20 weight percent of the polyol component. Preferable are theHCFCs having an ozone depletion potential of 0.05 or less. Otherreactive blowing agents may be used in conjunction with water, such astertiary alcohols and formic acid.

Flame retardants may also be used when required by the formulation.Suitable flame retardants are well known to those skilled in the art;but the low molecular weight halogenated phosphate esters,polyhalogenated biphenyls, biphenyloxides, and the like may be used whenflame retardants are necessary. As the presence of such flame retardantsgenerally causes a decrease in physical properties, use of flameretardants is not preferred.

Ultraviolet stabilizers and absorbers may also be useful. Suchstabilizers generally act by absorbing ultraviolet radiation. Many suchultraviolet absorbers are commercially available, such as the Uvinul®absorbers manufactured by BASF Corporation, Parisippany, NJ.

Suitable catalysts include both urethane and isocyanurate reactionpromoting catalysts and are well known to those skilled in the art ofpolyurethanes. Suitable polyurethane-promoting catalysts includetertiary amines such as, for example, triethylenediamine,N-methylmorpholine, N-ethylmorpholine, diethylethanolamine,N-cocomorpholine, 1-methyl-4-dimethylaminoethylpiperazine,3-methoxypropyldimethylamine, N,N,N'-trimethylisopropylpropylenediamine,3-diethylaminopropyldiethylamine, dimethylbenzylamine, and the like.Preferred catalysts are amine catalysts such as those commercialavailable from Air Products Chemical Company under the name of DABCO®33-LV. Other suitable catalysts are, for example, stannous chloride,dibutyltin di-2-ethyl hexanoate, stannous oxide, dibutyltin diacetate,dibutyltindilaurate, as well as other organometallic compounds such asare disclosed in U.S. Pat. No. 2,846,408. Suitable amounts of urethanecatalyst are 1 weight percent of the resin component, preferably lessthan 0.3 weight percent.

Isocyanurate promoting catalysts include potassium acetate and potassium2-ethylhexanoate, with potassium acetate being advantageously mixed as asolution in a glycol such as ethylene glycol.

A surface-active agent is also optional but may be used for productionof high grade polyurethane foam especially when polyols other than thetertiary amine polyols are employed. Surfactants prevent the foam fromcollapsing and promote fine uniform cell structures. Numeroussurface-active agents have been found satisfactory. Nonionicsurface-active agents are preferred. Of these, the nonionicsurface-active agents such as the 7ell-known silicones have been foundparticularly desirable. Other surface-active agents include polyethyleneglycol ethers of long chain alcohols, tertiary amine or alkanolaminesalts of long chain alkyl acid sulfate esters, alkyl sulfonic esters,and alkyl arylsulfonic acids. Preferred surfactants are DC190 and DC193,silicon-containing surfactants available from Dow-Corning, Midland,Mich.

The flexural modulus, heat distortion temperature, and rigidity of thematrix may be adjusted by varying the urethane/isocyanurate content ofthe product. The isocyanurate content is increased by increasing theratio of isocyanate (A side) to polyol (B side). In general, isocyanateindices of from 80 to about 700 are useful, preferably from 95 to about250, and most preferably from 95 to 120.

Methods of manufacturing RRIM moldings are well known in the art. Theresin components are mixed and maintained at tank temperatures from 75°F. to 95° F., preferably from 85° F. to 95° F. to reduce the viscosityof the resin. The resin component and the isocyanate component areimpingement mixed at pressures around 2,000 psi and injected at aboutatmospheric pressure into an open mold which is subsequently shut andclamped or at about 150-200 psi into a closed mold. The mold ispreheated at from 100° F. to 180° F., preferably from 130° F. to 150°F., more preferably around 140° F., and may contain a substrate such asvinyl laid up on one of the mold surfaces. The raw material is usuallycenter injected, after which the part is demolded after a period oftypically one-and-a-half (11/2) to four (4) minutes. By using thetertiary amine polyols of the present invention, especially apredominant amount of the monoethanolamine initiated tertiary aminepolyol of the invention, the reaction time is much quicker, reducing thecure and demold time to 60 seconds or less.

The following examples illustrate the nature of the invention and arenot intended to be limiting thereof. Unless otherwise stated, allformulation values are given in weight percent.

Polyol A is a graft polyol containing 30 eight percent 1:1 acrylonitrilestyrene solids suspended in a propylene oxide-ethylene oxide adduct oftrimethylolpropane having a 13 weight percent ethylene oxide cap, thegraft polyol having a nominal hydroxyl number of about 24.

Polyol B is a tertiary amine polyether polyol comprising a propyleneoxide-ethylene oxide adduct of ethylenediamine terminated with about 15weight percent ethylene oxide and having a nominal hydroxyl number of62.

Polyol C is a tertiary amine polyether polyol comprising a propyleneoxide-ethylene oxide adduct of monoethanolamine terminated with about 26weight percent ethylene oxide and containing about 55 weight percentpolyoxypropylene, having a nominal hydroxyl number of 500.

1,4-Butanediol is a chain extender.

DC-193 is an industry standard silicone surfactant commerciallyavailable from Air Products Corp.

T-12 is dibutyltin dilaurate acting to promote cure, commerciallyavailable from Air Products Corp.

I-460 is a 75/25 weight percent blend of butanediol andtriethylenediamine, respectively.

POLYCAT 46 is a 62/38 weight percent blend of glycol and potassiumacetate, respectively, available from Air Products Corp.

DABCO 33-LV is a 33/67 weight percent blend of TEDA and DP6,respectively, available from Air Products Corp.

Isocyanate A is a blend of isocyanates comprising about 60 weightpercent 4,4'-diphenylmethane diisocyanate, 5 weight percent2,4'-diphenylmethane diisocyanate, and 35 weight percent three-ringed orhigher oligomeric polymethylene polyphenylene polyisocyanates.

Isocyanate B is a 25 weight percent uretonimine-carbodiimide-modified4,4'-diphenylmethane diisocyanate and 75 weight percent4,4'-diphenylmethane diisocyanate.

Isocyanate C is a 50 weight percent glycol initiated urethane-modifiedprepolymer in 4,4'-diphenylmethane diisocyanate.

Isocyanate D is a 50/50 weight percent blend of Isocyanate B andIsocyanate C.

Isocyanate E is polymethylene polyphenylene polyisocyanate.

Filler A is a wollastonite fiber, an acicular calcium metasilicatecommercially available from NYCO Corp. under the name of G-RRIM™Wollastokup® having a 15:1 aspect ratio.

Filler B is one-sixteenth inch milled glass.

RESIN COMPONENT 1

Resin 1 is a blend made by the sequential addition of 35.9 weightpercent Polyol A; 14.55 weight percent of Polyol B; 20.36 weight percentof 1,4-butanediol; 0.73 weight percent of DC-193; 0.88 weight percent ofI-460; 0.08 weight percent of T-12; 0.40 weight percent of water; and27.10 weight percent of Filler A, each ingredient being mixed for 60seconds using a 3" German stirrer at 1700-3000 rpm.

RESIN COMPONENT 2

Using the same procedure as in Resin 1, 63.84 weight percent of PolyolC; 7.0 weight percent of Polyol B; 0.75 weight percent of POLYCAT 46;0.1 weight percent of DABCO 33-LV; 0.3 weight percent of water; 0.1weight percent of T-5; and 28 weight percent of Filler A were blended.

RESIN COMPONENT 3

Resin 3 is identical to Resin 2 except that Filler A was replaced withFiller B.

EXPERIMENT

The resins and isocyanates were combined in the proportions designatedbelow in Table I. Samples 1-4 were prepared by adding the isocyanate tothe resin batch and handmixing using a drill press with a three inchblade at 2340 rpm for 5 seconds and pouring the mixture into an aluminum10"×10"×1/16" mold preheated to about 140° F. and sprayed with asilicone release agent. The mold was clamped shut, and the materialallowed to react. The plaques were demolded and tested, the results ofwhich are reported in Table I.

Samples 5-6 were prepared using an Cannon and an EMB high pressureimpingement mixing machine, respectively, to inject the raw materials atabout 85° F. into a closed mold preheated to about 140° F. The moldcontained a vinyl backing lain in the female half, and about 1600 gramsof material was injected through the top half of the mold. The moldeddoor panel was demolded in 60 seconds and tested for its properties,also reported in Table I.

                                      TABLE I                                     __________________________________________________________________________    SAMPLE            1    2      3      4      5      6                          __________________________________________________________________________    ISOCYANATE A      --   --     --     --     83     83                         ISOCYANATE B      77.5 --     --     --     --     --                         ISOCYANATE C      --   --     99     --     --     --                         ISOCYANATE D      --   --     --     87     --     --                         ISOCYANATE E      --   72.6   --     --     --     --                         RESIN 1           100  100    100    100    --     --                         RESIN 2           --   --     --     --     100    --                         RESIN 3           --   --     --     --     --     100                        INDEX             100  100    100    100    100    100                        SPECIFIC GRAVITY  .58  .58    .54    .50    .65    .625                       THICKNESS         .14  .14    .14    .14    .1     .14                        FLEXURAL MODULUS AT                                                           72° F.     127,500                                                                            64,000 52,000 52,000 175,000                                                                              195,000                    -20° F.    --   120,000                                                                              120,000                                                                              110,000                                                                              --     --                         158° F.    --   27,000 4,500  14,000 --     --                         TENSILE (PSI)     1,900                                                                              1,400  1,600  1,400  2,100  1,740                      HARDNESS, SHORE A --   94     95     94     --     --                         ELONGATION (%)    5    5      9      7      3.0    3.5                        HDT (264 PSI) °F.                                                                        130  120    112    114    140    140                        CLTE % (24 HR.)   0.75 42 × 10.sup.-6                                                                 61 × 10.sup.-6                                                                 49 × 10.sup.-6                                                                 21 × 10.sup.-6                                                                 21 × 20.sup.-6       GARDNER IMPACT (IN./LB.)                                                      72° F.     12   6      8      10     6      6                          -20° F.    8    4      2      6      8      8                          DEMOLD TIME (SECONDS)                                                                           150  150    150    150    60     60                         __________________________________________________________________________

Sample 6 containing glass fiber reinforcement demolded in 60 seconds andhad good flexural modulus and impact strength for a low density RRIMpart prepared with a tertiary amine polyol. The results from Sample 5indicate that wollastonite is a low cost alternative to glass fiberreinforcement when one employs a predominant amount of tertiary aminepolyol. The wollastonite reinforced part made with the tertiary aminepolyol had comparable mechanical properties to the glass reinforcedpart. Samples 1-4 also exhibited suitable, although not preferable,properties when minor portions of tertiary amine polyol were employed ina wollastonite-filled part. However, Sample 1 demonstrated good overallproperties when uretonimine-carbodiimide-modified MDI is used as theisocyanate in the preparation of the matrix.

We claim:
 1. A rigid cellular polyurethane reinforced RIM composite witha specific gravity of less than 1.0, having wollastonite fibersdispersed throughout a matrix, said matrix comprising:A) an "A side"isocyanate component comprising one or more polyisocyanates, reactedwith, B) a "B side" component comprising a polyoxyalkylene polyetherpolyol composition comprising hydroxyl functional tertiary aminepolyether polyols prepared by oxyalkylating an amine with ethyleneoxide, propylene oxide, tetrahydrofuran, or mixtures thereof, a blowingagent comprising water, a polyurethane/isocyanurate-promoting catalyst,and optionally a chain extender, a surfactant, and stabilizers.
 2. Thecomposite of claim 1, wherein the specific gravity is 0.8 g/cm³ or less.3. The composite of claim 2, wherein the wollastonite fibers arecontained in the "B side" component prior to reaction with the "A side"component.
 4. The composite of claim 3, wherein all the polyolscontained in the "B side" component consist of hydroxyl functionaltertiary amine polyether polyols terminated with primary hydroxylgroups, and the "B side" resin component contains no chain extenders orcrosslinkers.
 5. The composite of claim 4, wherein said hydroxylfunctional tertiary amine polyether polyols are selected from the groupconsisting of monoalkanolamine-initiated polyols,alkylenediamine-initiated polyols, and mixtures thereof.
 6. Thecomposite of claim 5, wherein said hydroxyl functional tertiary aminepolyether polyols are selected from the group consisting ofmonoethanolamine-initiated polyols, ethylenediamine-initiated polyols,and mixtures thereof.
 7. The composite of claim 3, wherein 50 weightpercent to 99 weight percent of the reactive ingredients in the "B side"resin consist of hydroxyl functional tertiary amine polyether polyols.8. The composite of claim 3, wherein the "B side" resin further containsgraft polymer polyether polyol dispersions.
 9. The composite of claim 2,wherein the amount of wollastonite is from 10 weight percent to 20weight percent based on the weight of the composite.
 10. The compositeof claim 9, wherein the blowing agents consists of water.
 11. Thecomposite of claim 9, wherein the wollastonite fibers are acicular, havean aspect ratio of 10 or greater, and are from 0.03 inch to 0.25 inch inlength.
 12. The composite of claim 2, wherein the flexural modulus ofthe composite is from 150,000 psi to 210,000 psi at 72° F.